Tearinducing

Tearinducing describes substances or stimuli that provoke lacrimation, the production of tears, by stimulating the ocular surface or triggering reflex tearing through the trigeminal nerves. It can refer to chemical irritants, spicy compounds, or mechanical irritation that cause tearing as a protective response.

Tearing is produced by the lacrimal glands and occurs in basal, reflex, and emotional forms. Tearinducing stimuli typically irritate the cornea or conjunctiva, activating sensory nerves that send signals to the lacrimal glands and associated pathways. This reflex tearing helps flush out irritants and lubricate the eye. Some volatile irritants can also stimulate nasal or sinus receptors, contributing to tearing through interconnected reflex circuits. For example, certain alliums release a volatile lachrymatory factor that briefly activates tear production and eye irritation.

Common examples include onions and other alliums, which release lachrymatory compounds; tear gases such as CS gas used in riot control; pepper spray and other capsaicinoids that irritate mucous membranes; and various irritants like ammonia, acids, chlorine, dust, or smoke. In everyday life, tearinducing effects are usually transient and vary with individual sensitivity, environmental conditions, and exposure duration.

In addition to everyday phenomena, tearinducing agents are studied in ophthalmology and toxicology to understand ocular irritation and protective reflexes. They are also considered in safety testing and regulatory contexts to assess eye irritation potential. Terms closely related include lachrymogenic or lachrymator, used in reference to the capability or agents that cause tearing.